1. Field of the Invention
The present invention relates to a cap with valve, such as a fuel cap or a radiator cap for automobiles, which is installed to an aperture of a container such as a fuel tank or a radiator and adjusts pressure in the container by flowing fluid such as air out of the container or into the container from outside when the pressure in the container is positive or negative.
2. Description of the Prior Art
FIG. 1 shows inner structure of a cap with valve in the prior art, for example, a fuel cap to be installed to a filler neck of an automobile.
A fuel cap (hereinafter referred to as "cap") in FIG. 1 has inner structure where a cap body 1 to which an upper cover (not shown) is to be fitted is installed to a filler neck of a fuel tank and formed with a flow path 1a of fluid such as air, a spring shoe plate 2 is fixed by undercut to one end (top end) of the flow path 1a, a coil spring 3 is disposed at lower surface of the spring shoe plate 2, and an annular seal member 5 is fixed to bottom end of the coil spring 3 and a support plate 4 provided at the center with a fluid flowing hole 4a is arranged there. The annular seal member 5 is provided at outer circumferential portion with a lip element 5a abutting on a stepped portion 1b formed at inner circumference of the cap body fluid flow path 1a, and a valve plate 6 abuts on a lip element 5b at inner circumferential portion of the seal member 5 and is urged from other end (bottom end) of the cap body fluid flow path 1a so as to oppose the seal member 5 and close inner circumference of the seal member 5. A coil spring 7 to urge the valve plate 6 has bottom end abutting on a spring shoe 1c at bottom end of the cap body stepped portion 1b. In this connection, operation mode at positive pressure state and negative pressure state within the fuel tank will be described. When pressure in the fuel tank is positive, the seal member 5 and the support plate 4 are elevated against the biasing force of the spring 3, and since the outer lip element 5a of the seal member and the stepped portion 1b of the cap body are separated from each other, fluid such as air in the tank flows through the gap (refer to arrow indication .fwdarw.). On the contrary, when the pressure in the fuel tank is negative, the valve plate 6 is lowered against the biasing force of the spring 7, and since the inner lip element 5b of the seal member and the valve plate 6 are separated from each other, fluid such as air flows in the tank through the gap (refer to arrow indication .fwdarw.).
In the prior art, however, parts are assembled in sequence of the coil spring 7, the valve plate 6, the support plate 4 with the seal plate 5 fixed thereto, the coil spring 3, and the spring shoe plate 2 one after another. In this constitution, the number of parts to be inserted in the cap body fluid flow path 1a becomes large, the assembling work is troublesome, and the assembling in the shifted state of parts may be caused.